Freddi Segal-Gidan is Director of the Rancho Los Amigos/University of Southern California (USC) Alzheimer’s Disease Center and Assistant Clinical Professor in the departments of Neurology and Family Medicine at Keck School of Medicine, USC, and in Gerontology at L. Davis School of Gerontology at USC, Los Angeles.
PROGNOSIS The symptoms of iNPH are slowly progressive. Early recognition and intervention have been shown to improve outcomes.28 Long-term improvement following shunt surgery has been reported in up to 75% of patients when there is proper patient selection.13 A large body of literature has focused on proper patient selection and outcome predictors for shunting (see Table 2).
Gait and imbalance have repeatedly been reported to improve the most from shunting, particularly when gait disturbance precedes cognitive decline.29,30 Cognitive impairment, particularly once it reaches the degree of dementia, is least responsive to shunt placement, with only about 50% of patients experiencing improvement in cognition postsurgery.31
The SINPHONI study (Study of Idiopathic Normal Pressure Hydrocephalus on Neurological Improvement) conducted in Japan found that mild impairment in any of the triad symptoms (gait, cognition, urinary incontinence) prior to shunt surgery predicted disappearance of symptoms following surgery; in addition, younger age was a predictor of disappearance of gait disturbance.32 Complete disappearance of symptoms is often not achievable, but significant improvement in symptoms may be a more attainable outcome goal. Long-term follow-up has found that symptom improvement is sustained in up to 25% to 47% of patients over three to five years.33,34
